Multi-layer ground plane structures for integrated lead suspensions

ABSTRACT

Multi-layer ground plane structures and methods of manufacture for integrated lead suspension flexures. A flexure in accordance with one embodiment of the invention includes an insulating layer, a plurality of traces on the insulating layer and a stainless steel base layer on the side of the insulating layer opposite the traces. The stainless steel base layer includes one or more void portions with voids in the base layer opposite the insulating layer from the traces and one or more backed portions with the base layer backing the traces. A plurality of patterned and transversely-spaced first conductive ground planes are located opposite the insulating layer from the traces at the void portions and backed portions of the stainless steel base layer. A continuous gold second conductive ground plane is located opposite the insulating layer and the first ground planes from the side of the insulating layer adjacent to the traces at the void portions and backed portions of the stainless steel base layer. The gold ground plane can be used as an etch stop during formation of the voids in the base layer.

REFERENCE TO RELATED APPLICATION

This application is a division of U.S. application Ser. No. 11/681,402,filed Mar. 2, 2007 and entitled Multi-Layer Ground Plane Structures ForIntegrated Lead Suspensions, which is a continuation in part of U.S.application Ser. No. 11/548,177, filed Oct. 10, 2006 and entitledMulti-Layer Ground Plane Structures For Integrated Lead Suspensions,both of which are incorporated herein by reference in their entirety andfor all purposes.

FIELD OF THE INVENTION

The invention relates generally to integrated lead suspensions used indisk drives. In particular, the invention is a multiple-layer, highconductivity ground plane structure for an integrated lead suspension

BACKGROUND OF THE INVENTION

Integrated lead or wireless suspensions used to support the sliders andread/write heads in magnetic disk drives are well known and disclosed,for example, in the Akin, Jr. et al. U.S. Pat. No. 5,796,552 and theShiraishi et al. U.S. Pat. No. 6,891,700. These devices typicallyinclude a flexure mounted to a stainless steel load beam. The flexuretypically includes a stainless steel base with a plurality of conductiveleads or traces extending between terminal pads on the opposite ends ofthe device. A layer of polyimide or other insulating material separatesthe traces from the underlying stainless steel base. Subtractive andadditive processes can be used to manufacture these devices. Subtractivemanufacturing methods use photolithography and etching processes to formthe flexure from laminated material stock having a layer of stainlesssteel and a layer of conductive material separated by an insulatinglayer. Additive manufacturing methods use photolithography, depositionand etching processes to add the insulating layer, traces and otherstructures to a stainless steel base.

The stainless steel layer of the flexure acts as a ground plane for thetraces. Because the dielectric layer is usually relatively thin, thetraces and ground plane can be coupled. These electrical characteristicscan reduce the signal performance characteristics of the traces,especially at high signal frequencies. Approaches for compensating forthe impact of the stainless steel layer on the signal performancecharacteristics are known. For example, the Shiraishi et al. U.S. Pat.No. 6,891,700 discloses holes below the traces through the stainlesssteel layer of the flexure to lower parasitic capacitance. The Akin, Jr.et al. U.S. Pat. No. 5,796,552 discloses an embodiment having a shieldformed by electro-deposition of a metallic film against the dielectriclayer below the traces and a conductor shield over the traces.

There remains, however, a continuing need for integrated lead structuresproviding improved signal performance. To be commercially viable anysuch structures must be capable of being efficiently manufactured.

SUMMARY OF THE INVENTION

One embodiment of the present invention is an improved method formanufacturing an integrated lead suspension component such as a flexurehaving high-quality signal performance. The method includes: (1) formingone or more second conductive ground planes on a stainless steel baselayer, the material of the second conductive ground planes beingnon-reactive to a first etchant; (2) forming one or more firstconductive ground planes on the surface of at least portions of thesecond ground planes; (3) forming an insulating layer on the firstground planes; (4) forming traces on the insulating layer; and (5)forming voids in void portions of the stainless steel base layer usingthe first etchant and the second conductive ground planes as etch stops.The second conductive ground planes can be gold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a portion of an integrated lead flexure inaccordance with one embodiment of the present invention.

FIGS. 1A, 1B and 1C are cross sectional views of the integrated leadflexure shown in FIG. 1, taken at section lines A-A, B-B and C-C in FIG.1, respectively.

FIG. 2 is a top plan view of a portion of the integrated lead flexureportion shown in FIG. 1 during its manufacture in accordance with oneembodiment of the invention.

FIGS. 2A, 2B and 2C are cross sectional views of the integrated leadflexure portion shown in FIG. 2, taken at section lines A-A, B-B and C-Cin FIG. 2, respectively.

FIG. 3 is a top plan view of the integrated lead flexure portion shownin FIG. 2 following additional manufacturing steps in accordance withone embodiment of the invention.

FIGS. 3A, 3B and 3C are cross sectional views of the integrated leadflexure portion shown in FIG. 3, taken at section lines A-A, B-B and C-Cin FIG. 3, respectively.

FIG. 4 is a top plan view of the integrated lead flexure portion shownin FIG. 3 following yet additional manufacturing steps in accordancewith one embodiment of the invention.

FIGS. 4A, 4B and 4C are cross sectional views of the integrated leadflexure portion shown in FIG. 4, taken at section lines A-A, B-B and C-Cin FIG. 4, respectively.

FIG. 5 is a top plan view of a portion of an integrated lead flexure inaccordance with a second embodiment of the present invention.

FIGS. 5A, 5B and 5C are cross sectional views of the integrated leadflexure shown in FIG. 5, taken at section lines A-A, B-B and C-C in FIG.5, respectively.

FIG. 6 is a top plan view of a portion of the integrated lead flexureportion shown in FIG. 5 during its manufacture in accordance with oneembodiment of the invention.

FIGS. 6A, 6B and 6C are cross sectional views of the integrated leadflexure portion shown in FIG. 6, taken at section lines A-A, B-B and C-Cin FIG. 6, respectively.

FIG. 7 is a top plan view of the integrated lead flexure portion shownin FIG. 6 following additional manufacturing steps in accordance withone embodiment of the invention.

FIGS. 7A, 7B and 7C are cross sectional views of the integrated leadflexure portion shown in FIG. 7, taken at section lines A-A, B-B and C-Cin FIG. 7, respectively.

FIG. 8 is a top plan view of the integrated lead flexure portion shownin FIG. 7 following yet additional manufacturing steps in accordancewith one embodiment of the invention.

FIGS. 8A, 8B and 8C are cross sectional views of the integrated leadflexure portion shown in FIG. 8, taken at section lines A-A, B-B and C-Cin FIG. 8, respectively.

FIG. 9 is a top plan view of a portion of an integrated lead flexure inaccordance with another embodiment of the invention.

FIGS. 9A, 9B and 9C are cross sectional views of the integrated leadflexure portion shown in FIG. 9, taken at section lines A-A, B-B and C-Cin FIG. 9, respectively.

FIG. 10 is a top plan view of a portion of the integrated lead flexureportion shown in FIG. 9 during its manufacture in accordance with oneembodiment of the invention.

FIGS. 10A, 10B and 10C are cross sectional views of the integrated leadflexure portion shown in FIG. 10, taken at section lines A-A, B-B andC-C in FIG. 10, respectively.

FIG. 11 is a top plan view of the integrated lead flexure portion shownin FIG. 10 following yet additional manufacturing steps in accordancewith one embodiment of the invention.

FIGS. 11A, 11B and 11C are cross sectional views of the integrated leadflexure portion shown in FIG. 11, taken at section lines A-A, B-B andC-C in FIG. 11, respectively.

FIG. 12 is a top plan view of a portion of an integrated lead flexure inaccordance with another embodiment of the present invention.

FIGS. 12A, 12B and 12C are cross sectional views of the integrated leadflexure shown in FIG. 12, taken at section lines A-A, B-B and C-C inFIG. 12, respectively.

FIG. 13 is a top plan view of the integrated lead flexure portion shownin FIG. 12 during its manufacture in accordance with one embodiment ofthe invention.

FIGS. 13A, 13B and 13C are cross sectional views of the integrated leadflexure portion shown in FIG. 13, taken at section lines A-A, B-B andC-C in FIG. 13, respectively.

FIG. 14 is a top plan view of the integrated lead flexure portion shownin FIG. 13 following additional manufacturing steps in accordance withone embodiment of the invention.

FIGS. 14A, 14B and 14C are cross sectional views of the integrated leadflexure portion shown in FIG. 14, taken at section lines A-A, B-B andC-C in FIG. 14, respectively.

FIG. 15 is a top plan view of the integrated lead flexure portion shownin FIG. 14 following yet additional manufacturing steps in accordancewith one embodiment of the invention.

FIGS. 15A, 15B and 15C are cross sectional views of the integrated leadflexure portion shown in FIG. 15, taken at section lines A-A, B-B andC-C in FIG. 15, respectively.

FIG. 16 is a top plan view of a portion of an integrated lead flexure inaccordance with a yet another embodiment of the present invention.

FIGS. 16A, 16B and 16C are cross sectional views of the integrated leadflexure shown in FIG. 16, taken at section lines A-A, B-B and C-C inFIG. 16, respectively.

FIG. 17 is a top plan view of the integrated lead flexure portion shownin FIG. 16 during its manufacture in accordance with one embodiment ofthe invention.

FIGS. 17A, 17B and 17C are cross sectional views of the integrated leadflexure portion shown in FIG. 17, taken at section lines A-A, B-B andC-C in FIG. 17, respectively.

FIG. 18 is a top plan view of the integrated lead flexure portion shownin FIG. 17 following additional manufacturing steps in accordance withone embodiment of the invention.

FIGS. 18A, 18B and 18C are cross sectional views of the integrated leadflexure portion shown in FIG. 18, taken at section lines A-A, B-B andC-C in FIG. 18, respectively.

FIG. 19 is a top plan view of the integrated lead flexure portion shownin FIG. 18 following yet additional manufacturing steps in accordancewith one embodiment of the invention.

FIGS. 19A, 19B and 19C are cross sectional views of the integrated leadflexure portion shown in FIG. 19, taken at section lines A-A, B-B andC-C in FIG. 19, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a top view of a portion of an integrated lead flexure 8 (i.e.,a suspension component) having a multiple layer, high conductivityground plane structure 10 in accordance with one embodiment of theinvention. FIGS. 1A, 1B and 1C are sectional views of the flexure 8taken at lines A-A, B-B and C-C, respectively in FIG. 1. As shown,flexure 8 includes a stainless steel base layer 12, a plurality of leadsor traces 14 and a dielectric or insulating layer 16 separating thetraces from the base layer. The traces 14 extend between terminal pads(not shown) on the opposite ends of the flexure 8. The illustratedembodiment of flexure 8 has four traces 14 that are arranged in twogroups of two traces each. As shown in FIG. 1C (but not in FIGS. 1, 1Aor 1B), a conductive plating layer 23 can be applied over the surfacesof the traces 14 extending from the insulating layer 16. A dielectriccover layer 26 can also be applied over the plated traces 14 andoptionally over the insulating layer 16. Flexure 8 is configured to bemounted to a stainless steel or other conventional load beam in aconventional manner.

One or more portions 15 of the flexure 8 have stainless steel base layer12 below or backing the traces 14. One or more portions 13 of theflexure 8 (one is shown in FIGS. 1 and 1A-1C) have windows or voids 18in the base layer 12 below portions of the traces 14. Voids 18 extendthrough the base layer 12. In the illustrated embodiment, void 18 islocated between the outer edge portions 21 of the base layer 12. Inother embodiments (not shown) voids 18 extend across the full width ofthe flexure 8, and no edge portions such as 21 remain. Voids 18 can beone of several “windows” in the flexure 8 (such as the holes in theShiraishi et al. U.S. Pat. No. 6,891,700), or can extend for any desiredlength between the terminal pads (not shown) on the opposite ends of thetraces, including on the gimbal region and tail of the flexure (notshown). Portions of the base layer 12 will remain to allow the flexure 8to be welded or otherwise attached to a load beam (not shown).

Ground plane structure 10 includes patterned first conductive groundplanes 22 on the stainless steel-backed portions 15 and a continuoussecond ground plane 24 over both the stainless steel backed portions 15and the stainless steel void portions 13. The first conductive groundplane 22 is located on the stainless steel base layer 12, below thetraces 14 and insulating layer 16, on the portions of the flexure 8 thatdo not have voids 18 in the base layer. The illustrated embodimentincludes two transversely spaced first conductive ground planes 22, onebelow each of the two sets of traces 14. The second high conductivityground plane 24 is located: (1) directly over the base layer 12 on thoseportions of the base layer that are not below a first conductive groundplane 22 (i.e., between the base layer 12 and the insulating layer 16),(2) on the base layer for the portions of the base layer that are notcovered by the insulating layer, (3) directly over the first conductiveground plane 22 at locations where the first ground plane 22 is present(i.e., between the first conductive ground plane 22 and the insulatinglayer 16), and (4) on the surface of the insulating layer opposite theinsulating layer surface with the traces 14 at the portions of theflexure where there are voids 18 in the stainless steel base layer 12.

FIGS. 2, 2A-2C, 3, 3A-3C and 4, 4A-4C illustrate an additive process bywhich the flexure 8 can be fabricated. As shown in FIGS. 2 and 2A-2C,the first conductive ground planes 22 are formed at desired locations onstainless steel stock 12′. The ground planes are formed from copper orcopper alloy in one embodiment. Other conductive metals or othermaterials are used in other embodiments. Photolithography andelectroplating processes are used to form the first ground planes 22 inone embodiment. Other processes such as sputtering or vapor depositionare used in other embodiments.

The second ground plane 24 is then formed over the stainless steel stock12′ and the first ground planes 22 as shown in FIGS. 3 and 3A-3C. In oneembodiment of the invention the second ground plane 24 is a layer ofgold that is sputtered onto the surfaces of the stainless steel stock12′ and first ground planes 22. In other embodiments, the second groundplane is a layer of other metal such as chromium or molybdenum. In theembodiment of the invention illustrated in FIGS. 3 and 3A-3C, the secondground plane 24 is sputtered onto the entire surface of the stainlesssteel stock 12′ and first ground planes 22. In other embodiments thesecond ground plane can be applied in desired patterns over onlyselected portions of the stainless steel stock 12′ and/or first groundplanes 22. Photolithography and other processes such as electroplatingcan also be used to form and optionally pattern the second ground plane24.

Insulating layer 16 can be formed over the second ground plane 24 andany exposed portions of stainless steel stock 12′ as shown in FIGS. 4and 4A-4C. In one embodiment of the invention the insulating layer 16 isformed by coating, curing and patterning a polyimide precursor. Othermaterials and processes are used in other embodiments. In theillustrated embodiment the insulating layer 16 extends across a width ofthe flexure 8 spanning both of the first ground planes 22 and the areabetween the first ground planes, but not the full width of the stainlesssteel stock 12′. In other embodiments (not shown), the insulating layercan take other configurations. Other processes can also be used to formthe insulating layer 16.

Traces 14 are formed on the insulating layer 16. In one embodiment ofthe invention a seed layer of conductive material is sputtered onto theinsulating layer 16 and patterned using photolithography and etchingprocesses. The traces 14 are then electroplated onto the seed layer. Anyconductive plating layer such as 23 (FIG. 1C) can then be plated ontothe traces 14. Photolithography and other processes such as vapordeposition and chemical etching can also be used to form the traces 14on the insulating layer 16. Cover layer 26 (FIG. 1C) can be formed overthe traces 14 using materials and processes such as those describedabove for forming the insulating layer 16.

Voids 18 and other structures in the stainless steel base layer 12 offlexure 8 are formed from the stainless steel stock by photolithographyand etching processes in one embodiment of the invention. By way ofexample, a mask (not shown) corresponding to the patterns of voids 18can be formed on the side of stainless steel stock 12′ opposite theinsulating layer 16, and the stainless steel stock exposed to a chemicaletchant. In one embodiment of the invention, the etchant used to removethe stainless steel stock 12′ at voids 18 is not reactive to thematerial used for the second ground plane 24. In these embodiments thesecond ground plane 24 can be used as an etch stop during themanufacture of flexure 8, thereby enhancing the efficiency of themanufacturing process. In the embodiment described above that has a goldsecond ground plane 24, for example, the ground plane will function asan etch stop for an etching process using FeCl acid to form voids 18.

FIG. 5 is a top view of a portion of an integrated lead flexure 108having a multiple layer, high conductivity ground plane structure 110 inaccordance with another embodiment of the invention. FIGS. 5A, 5B and 5Care sectional views of the flexure 108 taken at lines A-A, B-B and C-C,respectively in FIG. 5. As shown, flexure 108 includes a stainless steelbase layer 112, a plurality of leads or traces 114 and a dielectric orinsulating layer 116 separating the traces from the base layer. Thetraces 114 extend between terminal pads (not shown) on the opposite endsof the flexure 108. The illustrated embodiment of flexure 108 has fourtraces 114 that are arranged in two groups of two traces each. As shownin FIG. 5C (but not in FIGS. 5, 5A or 5B), a conductive plating layer123 can be applied over the surfaces of the traces 114 extending fromthe insulating layer 116. A dielectric cover layer 126 can also beapplied over the plated traces 114 and optionally over the insulatinglayer 116. Flexure 108 is configured to be mounted to a stainless steelor other conventional load beam (not shown) in a conventional manner.

One or more portions 115 of the flexure 108 have the stainless steelbase layer 112 below or backing the traces 114. One or more portions 113of the flexure 108 (one is shown in FIGS. 5 and 5A-5C) have windows orvoids 118 in the base layer 112 below portions of the traces 114. Voids118 extend through the base layer 112. In the illustrated embodiment,void 118 is located between the outer edge portions 121 of the baselayer 112. In other embodiments (not shown) voids 118 extend across thefull width of the flexure 108, and no edge portions such as 121 remain.Voids 118 can be one of several “windows” in the flexure 108 (such asthe holes in the Shiraishi et al. U.S. Pat. No. 6,891,700), or canextend for any desired length between the terminal pads (not shown) onthe opposite ends of the traces, including on the gimbal region and tailof the flexure (not shown). Portions of the base layer 112 will remainto allow the flexure 108 to be welded or otherwise attached to a loadbeam (not shown).

Ground plane structure 110 includes patterned first conductive groundplanes 122 on the stainless steel-backed portions 115 and patternedsecond ground planes 124 over both the stainless steel backed portions115 and the stainless steel void portions 113. The first conductiveground planes 122 are located on the stainless steel base layer 112,below the traces 114 and insulating layer 116, on the portions of theflexure 108 that do not have voids 118 in the base layer. Theillustrated embodiment includes two transversely spaced first conductiveground planes 122, one below each of the two sets of traces 114. Thesecond high conductivity ground plane 124 is located: (1) over the firstground planes 122, and (2) below the traces 114 at the stainless steelvoid portions 113 (between the stainless steel voids 113 and theinsulating layer 116).

FIGS. 6, 6A-6C, 7, 7A-7C and 8, 8A-8C illustrate an additive process bywhich the flexure 108 can be fabricated. As shown in FIGS. 6 and 6A-6C,the first conductive ground planes 122 are formed at desired locationson stainless steel stock 112′. The ground planes 122 are formed fromcopper or copper alloy in one embodiment. Other conductive metals orother materials are used in other embodiments. Photolithography andelectroplating processes are used to form the first ground planes 122 inone embodiment. Other processes such as sputtering or vapor depositionare used in other embodiments. As described below, portions of theground planes 122 formed during this manufacturing step at stainlesssteel void portions 113 will be removed during subsequent manufacturingsteps.

The second ground planes 124 are then formed over the first groundplanes 122 as shown in FIGS. 7 and 7A-7C. In one embodiment of theinvention the second ground planes 124 are a layer of gold that iselectroplated onto the surfaces of the first ground planes 122. In otherembodiments, the second ground plane is a layer of other metal such aschromium or molybdenum. In the embodiment shown, the second groundplanes 124 are pattern electroplated onto the first ground planes 122using the same photoresist pattern mask that was used during theformation of the first ground planes. In other embodiments (not shown)the second ground planes 124 can also be formed in desired patterns overselected portions of the stainless steel stock 112′ and/or first groundplanes 122. Photolithography and other processes such as sputtering andvapor deposition can also be used to form and optionally pattern thesecond ground planes 124.

Insulating layer 116 can be formed over the second ground planes 124 andany exposed portions of stainless steel stock 112′ as shown in FIGS. 8and 8A-8C. In one embodiment of the invention the insulating layer 116is formed by coating, curing and patterning a polyimide precursor. Othermaterials and processes are used in other embodiments. In theillustrated embodiment the insulating layer 116 extends across a widthof the flexure 108 spanning both of the first ground planes 122 and thearea between the first ground planes, but not the full width of thestainless steel stock 112′. In other embodiments (not shown), theinsulating layer can take other configurations. Other processes can alsobe used to form the insulating layer 116.

Traces 114 are formed on the insulating layer 116. In one embodiment ofthe invention a seed layer of conductive material is sputtered onto theinsulating layer 116 and patterned using photolithography and etchingprocesses. The traces 114 are then electroplated onto the seed layer.Any conductive plating layer such as 123 (FIG. 5C) can then be platedonto the traces 114. Photolithography and other processes such as vapordeposition and chemical etching can also be used to form the traces 114on the insulating layer 116. Cover layer 126 (FIG. 5) can be formed overthe traces 114 using materials and processes such as those describedabove for forming the insulating layer 116.

Voids 118 and other structures in the stainless steel base layer 112 offlexure 108 are formed from the stainless steel stock 112′ byphotolithography and etching processes in one embodiment of theinvention. By way of example, a mask (not shown) corresponding to thepatterns of voids 118 can be formed on the side of stainless steel stock112′ opposite the insulating layer 116, and the stainless steel stockexposed to a chemical etchant. In one embodiment of the invention, theetchant used to remove the stainless steel stock 112′ at voids 118 isnot reactive to the material used for the second ground planes 124. Inthese embodiments the second ground plane 124 can be used as an etchstop during the manufacture of flexure 108, thereby enhancing theefficiency of the manufacturing process. In the embodiment describedabove that has a gold second ground planes 124, for example, the groundplane will function as an etch stop for an etching process using FeClacid to form voids 118. In this embodiment where the first ground planes122 are copper or copper alloy, the etchant will also remove (not shown)the first ground planes 122 at the location of the voids 118.

FIG. 9 is a top view of a portion of an integrated lead flexure 208having a multiple layer, high conductivity ground plane structure 210 inaccordance with one embodiment of the invention. FIGS. 9A, 9B and 9C aresectional views of the flexure 208 taken at lines A-A, B-B and C-C,respectively in FIG. 9. As shown, flexure 208 includes a stainless steelbase layer 212, a plurality of leads or traces 214 and a dielectric orinsulating layer 216 separating the traces from the base layer. Thetraces 214 extend between terminal pads (not shown) on the opposite endsof the flexure 208. The illustrated embodiment of flexure 208 has fourtraces 214 that are arranged in two groups of two traces each. As shownin FIG. 9C (but not in FIGS. 9, 9A or 9B), a conductive plating layer223 can be applied over the surfaces of the traces 214 extending fromthe insulating layer 216. A dielectric cover layer 226 can also beapplied over the plated traces 214 and optionally over the insulatinglayer 216. Flexure 208 is configured to be mounted to a stainless steelor other conventional load beam (not shown) in a conventional manner.

One or more portions 215 of the flexure 208 have stainless steel baselayer 212 below or backing the traces 214. One or more portions 213 ofthe flexure 208 (one is shown in FIGS. 9 and 9A-9C) have windows orvoids 218 in the base layer 212 below portions of the traces 214. Voids218 extend through the base layer 212. In the illustrated embodiment,void 218 is located between the outer edge portions 221 of the baselayer 212. In other embodiments (not shown) voids 218 extend across thefull width of the flexure 208, and no edge portions such as 221 remain.Voids 218 can be one of several “windows” in the flexure 208 (such asthe holes in the Shiraishi et al. U.S. Pat. No. 6,891,700), or canextend for any desired length between the terminal pads (not shown) onthe opposite ends of the traces, including on the gimbal region and tailof the flexure (not shown). Portions of the base layer 212 will remainto allow the flexure 208 to be welded or otherwise attached to a loadbeam (not shown).

Ground plane structure 210 includes patterned first conductive groundplanes 222 on the stainless steel-backed portions 215 and a continuoussecond ground plane 224 over both the stainless steel backed portions215 and the stainless steel void portions 213. The first conductiveground plane 222 is located on the stainless steel base layer 212, belowthe traces 214 and insulating layer 216, on the portions of the flexure208 that do not have voids 218 in the base layer. The illustratedembodiment includes two transversely spaced first conductive groundplanes 222, one below each of the two sets of traces 214. In theillustrated embodiment the second high conductivity ground plane 224 islocated: (1) over the entire surface of the stainless steel base layer212 opposite the insulating layer 216, including the edges of the baselayer in the voids 218, and (2) over the surface of the insulating layer216 in the voids 218 (i.e., the surface of the insulating layer oppositethe traces 214).

FIGS. 10, 10A-10C, 11 and 11A-11C illustrate an additive process bywhich the flexure 208 can be fabricated. As shown in FIGS. 10 and10A-10C, the first conductive ground planes 222 are formed at desiredlocations on stainless steel stock 212′. The ground planes are formedfrom copper or copper alloy in one embodiment. Other conductive metalsor other materials are used in other embodiments. Photolithography andelectroplating processes are used to form the first ground planes 222 inone embodiment. Other processes such as sputtering or vapor depositionare used in other embodiments.

Insulating layer 216 can be formed over the first ground planes 222 andexposed portions of stainless steel stock 212′ as shown in FIGS. 11 and11A-11C. In one embodiment of the invention the insulating layer 216 isformed by coating, curing and patterning a polyimide precursor. Othermaterials and processes are used in other embodiments. In theillustrated embodiment the insulating layer 216 extends across a widthof the flexure 208 spanning both of the first ground planes 222 and thearea between the first ground planes, but not the full width of thestainless steel stock 212′. In other embodiments (not shown), theinsulating layer can take other configurations. Other processes can alsobe used to form the insulating layer 216.

Traces 214 are formed on the insulating layer 216. In one embodiment ofthe invention a seed layer of conductive material is sputtered onto theinsulating layer 216 and patterned using photolithography and etchingprocesses. The traces 214 are then electroplated onto the seed layer.Any conductive plating layer such as 223 (FIG. 9C) can then be platedonto the traces 214. Photolithography and other processes such as vapordeposition and chemical etching can also be used to form the traces 214on the insulating layer 216. Cover layer 226 (FIG. 9C) can be formedover the traces 214 using materials and processes such as thosedescribed above for forming the insulating layer 216.

Voids 218 and other structures in the stainless steel base layer 212 offlexure 208 are formed from the stainless steel stock byphotolithography and etching processes in one embodiment of theinvention. By way of example, a mask (not shown) corresponding to thepatterns of voids 218 can be formed on the side of stainless steel stock212′ opposite the insulating layer 216, and the stainless steel stockexposed to a chemical etchant.

The second ground plane 224 is then formed over the stainless steel baselayer 212 and the portions of insulating layer 216 exposed within thevoids 218 as shown in FIGS. 9 and 9A-9C. In one embodiment of theinvention the second ground plane 224 is a layer of gold that issputtered onto the surfaces of the stainless steel base layer 212 andinsulating layer 216. In other embodiments, the second ground plane is alayer of other metal such as chromium or molybdenum. In the oneembodiment of the invention the second ground plane 224 is sputteredonto the entire surface of the base layer 212 and the exposed portionsof the insulating layer 216. In other embodiments the second groundplane can be applied in desired patterns over only selected portions ofthe base layer 212 and the exposed portions of the insulating layer 216.Photolithography and other processes such as electroplating can also beused to form and optionally pattern the second ground plane 224.

FIG. 12 is a top view of a portion of an integrated lead flexure 8′having a multiple layer, high conductivity ground plane structure 10′ inaccordance with another embodiment of the invention. FIGS. 12A, 12B and12C are sectional views of the flexure 8′ taken at lines A-A, B-B andC-C, respectively, in FIG. 12. FIGS. 13, 13A-13C, 14, 14A-14C, 15 and15A-15C illustrate an additive process by which the flexure 8′ can befabricated. With the exception of the differences described below,integrated lead flexure 8′ and the processes by which it can bemanufactured can be the substantially the same as or similar to those offlexure 8 described above, and similar reference numbers are used toidentify similar features in the drawing figures.

Ground plane structure 10′ of flexure 8′ includes patterned andtransversely-spaced first ground planes 22′ and continuous second groundplane 24′ over both the stainless steel backed portions 15′ andstainless steel void portions 13′. The second conductive ground plane24′, which is gold in one embodiment of the invention (but other metalssuch as chromium or molybdenum in other embodiments), is located on thestainless steel base layer 12′, and in the illustrated embodiment isformed on the surface of the stainless steel base layer before the voids18′ are formed. Second ground plane 24′ is continuous in that it extendsover all or significant portions of the stainless steel base layer 12′in both the transverse and longitudinal directions, including portionsof the stainless steel base layer between the first ground planes 22′.The first ground planes 22′, which are copper or copper alloy in oneembodiment of the invention, are formed on the surface of the secondground plane 24′ opposite the stainless steel base layer 12′ atlocations below the traces 14′. The first ground planes 22′ arecontinuous in that they extend between adjacent stainless steel voidportions 13′ and stainless steel backed portions 15′ withoutdiscontinuities. In other embodiments of flexure 8′ (not shown) thefirst ground planes are discontinuous and do not extend over some or allof the void portions of the stainless steel base layer

At both the stainless steel void portions 13′ and the stainless steelbacked portions 15′ the second ground plane 24′ is located opposite theinsulating layer 16′ and (in the area directly under the traces 14′) thefirst ground planes 22′ from the side of the insulating layer on whichthe traces are located. The second ground plane 24′ can function as anetch stop during the etching of voids 18′, and is exposed in the voidsfollowing the etching process.

A thin layer 27′ of copper, copper alloy or other adhesion-enhancingmaterial is formed over portions of the second ground plane 24′ thatwere not covered by the first ground planes 22′ (e.g., in the areasbetween the first ground planes) to enhance the ability of theinsulating layer 16′ to adhere to the second ground plane. In theillustrated embodiment the adhesion-enhancing layer 27′ is also formedover the first ground planes 22′. In one embodiment of the inventionlayer 27′ is a layer of copper that is sputter deposited onto theflexure 8′.

FIG. 16 is a top view of a portion of an integrated lead flexure 108′having a multiple layer, high conductivity ground plane structure 110′in accordance with another embodiment of the invention. FIGS. 16A, 16Band 16C are sectional views of the flexure 108′ taken at lines A-A, B-Band C-C, respectively, in FIG. 16. FIGS. 17, 17A-17C, 18, 18A-18C, 19and 19A-19C illustrate an additive process by which the flexure 108′ canbe fabricated. With the exception of the differences described below,integrated lead flexure 108′ and the processes by which it can bemanufactured can be the substantially the same as or similar to those offlexure 108 described above, and similar reference numbers are used toidentify similar features in the drawing figures.

Ground plane structure 110′ of flexure 108′ includes patterned firstground planes 122′ and patterned second ground planes 124′. The secondground planes 124′, which are gold in one embodiment of the invention(but other metals such as chromium or molybdenum in other embodiments),are formed on the surface of the stainless steel base layer 112′ belowthe locations of the traces 114′ before the voids 118′ are formed. Thefirst ground planes 122′, which are copper or copper alloy in oneembodiment of the invention, are formed on the surface of the secondground planes 124′ opposite the stainless steel base layer 112′. Theportions of second ground planes 124′ located over the stainless steelbacked portions 115′ of the flexure 108′ are therefore between thestainless steel layer 112′ and the first ground planes 122′. Unlike theground planes 122 and 124 in the flexure 108 described above, groundplanes 122′ and 124′ of flexure 108′ can be continuous at theintersections of the stainless steel void portions 113′ and thestainless steel backed portions 115′ (but are discontinuous and spacedfrom one another along the transverse dimension of the flexure). Thesecond ground planes 124′ can function as an etch stop during theetching of voids 118′, and are exposed in the voids following theetching process. In other embodiments of flexure 108′ (not shown) thefirst ground planes are discontinuous and do not extend over some or allof the void portions of the stainless steel base layer.

Ground plane structures of the type described herein can be formed atany desired location on a flexure between the terminal pads at the tailand slider mounting region of the flexure. These ground planes offerimportant advantages. For example, they can reduce the overall impedanceof the traces between the terminal pads, as well as make the impedancemore uniform along the length of the traces. Signal transmissionperformance capabilities of the flexure such as peak current capacity,bandwidth and rise times are thereby enhanced. These advantages areachieved without detrimental impact to the mechanical functionality ofthe flexure. Furthermore, these structures can also be manufactured byefficient processes.

Although the present invention has been described with reference topreferred embodiments, those skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the invention. For example, although described inconnection with an integrated lead flexure for attachment to a loadbeam, the invention can be used in connection with other suspensioncomponents such as an integrated lead suspension.

1. A method for manufacturing an integrated lead suspension component,including: forming one or more second conductive ground planes on astainless steel base layer, the material of the second conductive groundplanes being non-reactive to a first etchant; forming one or more firstconductive ground planes on the surface of at least portions of thesecond conductive ground planes; forming an insulating layer on thefirst ground planes; forming traces on the insulating layer; and formingvoids in void portions of the stainless steel base layer using the firstetchant and the second conductive ground planes as etch stops.
 2. Themethod of claim 1 wherein: forming one or more second conductive groundplanes includes forming a continuous second ground plane on thestainless steel base layer; forming one or more first conductive groundplanes includes forming patterned first conductive ground planes overonly portions of the continuous second ground plane; the method furtherincludes forming an insulation adhesion-enhancing layer over portions ofthe second ground plane that are not covered by the first conductiveground planes; and forming the insulating layer includes forming theinsulating layer on the insulation adhesion-enhancing layer.
 3. Themethod of claim 2 wherein: forming the insulation adhesion-enhancinglayer further includes forming the insulation adhesion enhancing layerover the first conductive ground planes.
 4. The method of claim 1wherein forming the second conductive ground plane includes forming aplurality of patterned and transversely-spaced second ground planes. 5.The method of claim 1 wherein forming the one or more second conductiveground planes includes forming a layer of gold.
 6. The method of claim 5wherein forming the one or more first conductive ground planes includesforming a layer of copper or copper alloy.